This invention relates generally to the field of determining postal charges for mailpieces, and more particularly to measuring dimensions of mailpieces for dimension-based postal rating schemes.
In the operation of many postal authorities, the postal charges assessed for carriage of letters are based on the weight of the letters. However, alternative schemes have been proposed in which postal charges may also be based on one or more dimensions of the letters, such as, for example, thickness of the letters. To facilitate operation of such schemes, it has been proposed to automatically measure the thickness of letters using sensors that physically contact the letters. However, such mechanisms may prove to be inaccurate or unreliable, or may be prone to jamming as letters are transported past the sensors.
Optical techniques for measuring at least one dimension of a letter have also been proposed. It would be desirable for an optical technique for measuring letter dimensions that it measure two or three dimensions, and/or that it not require complex image processing.